Outgassing (sometimes called offgassing, particularly when in reference to indoor air quality) is the release of a gas that was dissolved, trapped, frozen or absorbed in some material. As an example, research has shown how the concentration of carbon dioxide in the Earth's atmosphere has sometimes been linked to ocean outgassing. It can include sublimation and evaporation which are phase transitions of a substance into a gas, as well as desorption, seepage from cracks or internal volumes and gaseous products of slow chemical reactions. Boiling is generally thought of as a separate phenomenon from outgassing because it consists of a phase transition of a liquid into a vapor made of the same substance.

Outgassing is a challenge to creating and maintaining clean high-vacuum environments. NASA and ESA maintains a list of low-outgassing materials to be used for spacecraft, as outgassing products can condense onto optical elements, thermal radiators, or solar cells and obscure them. Materials not normally considered absorbent can release enough light-weight molecules to interfere with industrial or scientific vacuum processes. Moisture, sealants, lubricants, and adhesives are the most common sources, but even metals and glasses can release gases from cracks or impurities. The rate of outgassing increases at higher temperatures because the vapour pressure and rate of chemical reaction increases. For most solid materials, the method of manufacture and preparation can reduce the level of outgassing significantly. Cleaning surfaces or baking individual components or the entire assembly before use can drive off volatiles.

Robert George Dylan Willis MBE (born Robert George Willis on 30 May 1949), known as Bob Willis, is a former English cricketer who played for Surrey, Warwickshire, Northern Transvaal and England. A right-handed and aggressive fast bowler with a notably long run-up, Willis spearheaded several England bowling attacks between 1971 and 1984, across 90 Test matches in which he took 325 wickets at 25.20 runs per wicket, at the time second only to Dennis Lillee. He is currently behind only Ian Botham as England's leading wicket taker. Willis took 899 first-class wickets overall, although from 1975 onwards he bowled with constant pain, having had surgery on both knees. He nevertheless continued to find success, taking a Test career best eight wickets for 43 runs in the 1981 Ashes series against Australia, one of the all-time best Test bowling performances, in the famous 1981 Ashes series against Australia. He was Wisden Cricketer of the Year for 1978.

In addition to the Test arena, Willis played 64 One Day International matches for his country, taking 80 wickets, and was a prolific List-A (one day) cricketer with 421 wickets overall at 20.18. With the bat, Willis made little impression as a tail-ender with a best Test score of 28 not-out (*); however, he managed two half-centuries at first-class level and for a time held a record number of Test not-outs. Willis captained the England team in 18 Tests and 28 ODI matches between June 1982 and March 1984. Under Willis' captaincy England won seven, lost five and drew six Tests, and won 16 of the ODIs. Botham recalled Willis as "a tremendous trier.. a great team-man and an inspiration", as well as the "only world-class fast bowler in my time as an England player." The editor of Wisden wrote of him in similar terms: "His indomitable service to England is handsomely reflected in his great collection of Test wickets. Although often beset with aches and pains, he never spared himself when bowling for his country."